1. Field of the Invention
The present invention relates to a lithium ion conductive glass-ceramics and a raw glass of a lithium ion conductive glass-ceramics.
2. Description of the Related Art
All solid lithium ion secondary batteries are proposed as safe lithium ion secondary batteries free of combustible organic solvents. In these all solid batteries, lithium ion conductivity is achieved not by nonaqueous electrolyte solutions but by solid electrolytes. Solid electrolytes have lower ion conductivity than nonaqueous electrolyte solutions. Therefore, improvement of lithium ion conductivity of solid electrolytes has been required.
Improvement of lithium ion conductivity is also required for the use of lithium ion conductive solid electrolytes in lithium-air batteries.
As solid electrolytes having high lithium ion conductivity, Japanese Patent Application Laid-Open Nos. 9-142874, 10-97811, and 10-182184 propose lithium ion conductive glass-ceramics. Lithium ion conductive glass-ceramics is produced by molding molten glass, and then heat treating the molded glass to precipitate (crystallize) lithium ion conductive crystallines. Since lithium ion conductive glass-ceramics is produced through these processes, it contains less voids causing the decrease in lithium ion conductivity than ceramic produced by sintering a ceramic powder. Therefore, the glass solid electrolytes have higher lithium ion conductivity than ceramic solid electrolytes.